Optimization of a finned concentric pipes heat exchanger for industrial recuperative burners

• A systematic method for the optimization of a double pipe heat exchanger is proposed.
• The method adopts CFD and a constrained version of the simplex optimization algorithm.
• The exchanger efficiency is optimized under different operating conditions.
• A resistance network analysis is included to address possible further improvements.
• The economic impact of the optimized solution in industrial kilns is estimated.

A numerical application is presented in which a finned concentric pipes heat exchanger is simulated by means of CFD, and optimized by the Nelder and Mead simplex downhill optimization algorithm. The heat exchanger parameterization takes into consideration the main geometrical aspects of the exchanger under different operating conditions. The work originates from an industrial problem related to heat recovery issues in recuperative burners, in which air is pre-heated by the exhaust gas before entering the combustion chamber. Such a device allows for an in situ and more efficient heat recovery from exhaust gases, also reducing both the sizing of the heat recovery system downstream to the furnace, and the burner fuel consumption. It is found that the fine tuning of just a few geometrical parameters can result in a sensible enhancement of the exchanger efficiency.